References [1], [2] and [3] describe devices capable of collecting random or non-specific (as opposed to target-specific) images of water motions in a marine environment by using a laser light source to illuminate ambient particles in the water and by using a video camera to record those motions. The devices cannot measure a specific target (e.g. animal-water interaction) because they are left at one location on the ocean floor, or they are made neutrally buoyant and carried by ambient water currents. The devices require a link to the surface for purposes of remote control, data storage, and/or supply of the light source via fiber optic links. These external connections limit the spatial range of the device to a fixed radius around the surface connection point. The required external connections and the relatively large size of the devices (up to 1000 kilograms) make them unsuitable for operation by a SCUBA diver.
Reference [4] describes a device capable of collecting random or non-specific (as opposed to target-specific) images of water motions in a marine environment by using a free-falling video camera to record the motion of ambient particles in the water that are illuminated by a free-falling laser light source. Since the device is free-falling, the images the device collects are wholly determined by its vertical trajectory in the water as it falls. Therefore, the device cannot collect target-specific images. The device requires a link to the surface for purposes of remote control, data storage, and/or supply of the light source via fiber optic links. The free-falling nature of the device, the required external connections, and its relatively large size (up to 1000 kilograms) make it unsuitable for operation by a SCUBA diver.
Reference [5] describes a device capable of collecting images of water motions in fluvial environments (i.e. rivers). Similarly to the apparatuses of the previously mentioned references, the device collects images of water motions by using a laser light source to illuminate ambient particles in the water and by using a video camera to record those motions. The device is kept stationary in the water and requires a link to the shore for the purpose of remote control. Due its stationary nature, the device is incapable of tracking moving targets. In addition, its external connection limits the spatial range of the device to a fixed radius around the surface connection point. The external connection also makes the device unsuitable for operation by a SCUBA diver.
Various remotely-operated and SCUBA diver-operated devices have been designed for the purpose of target-specific video recordings of marine life. Devices in the former group (e.g., devices made by the company SeaBotix, Inc.) require external connections to the surface, similar to the limitation of the devices described above. In addition, the propulsion units on the devices can startle and/or damage sensitive marine life. Devices in both groups are capable of recording biological life, but not the water motions around them.